1. Field of the Invention
This invention relates to heat exchangers and especially to heat exchangers adapted for recovering waste heat from furnaces, hot water heaters or the like.
2. Discussion of Related Art
It has been known for many years to attempt to recapture waste heat from the exhaust pipe or flue of an existing stove, furnace or the like. For instance, U.S. Pat. No. 1,060,415, issued Apr. 29, 1913 to Ayres shows a flue having a deflector disposed therein for channeling exhaust gases to a heat exchanger drum. Transverse radiator pipes extend through the drum for heating air passing through the pipes. U.S. Pat. No. 2,189,749, issued Feb. 13, 1940 to Windheim et al, shows a waste heating system including a water heating unit having spaced inner and outer casings, the space between the casings constituting a flue passage. Vertical flue tubes extend the length of the inner casing and a water wheel is contained within the inner casing and a water coil is contained within the inner casing and surrounds the flue tubes. The exhaust gases from a conventional furnace are channeled through the vertical flue tubes. U.S. Pat. No. 2,343,542, issued Mar. 7, 1944 to Faunce, shows a heat exchanger for connection in a pipe leading from a heating system. The heat exchanger has a lower casing with an open top and an upper casing disposed on the lower casing. Tubes extend through and are sealed to the ends of the upper casing. A tapered hood connects the intake end of the upper casing with an exit from a furnace. Other patents showing similar heat exchanger structure include U.S. Pat. No. 2,920,265, issued Sept. 1, 1959 to Dubovick, U.S. Pat. No. 2,882,023, issued Apr. 14, 1959 to Rizzo, and U.S. Pat. No. 4,103,735, issued Aug. 1, 1978 to Warner. Even though there are numerous heat exchanger structures which are useful, there exists a constant need for such structures which are more efficient, less costly, and easier to install and use.